I have experience with clonidine, both oral and transdermal patch. Clonidine is not considered a first-line drug, and if your doctor prescribed it alone, it suggest that you have very elevated BP readings because clondine is powerful. It is classified as an alpha agonist. The oral med acts relatively fast reaching peak effect in 2 hours. The dermal patch is slower acting and takes two days to become effective; it provides a steady dose, but often causes burns and rash on the skins (I could no longer tolerate them after two months use).  

Oral clondine is hard to use to effectively control BP spikes because you tend to over or under control with it because of its short-acting nature. Side effects from clondine include sedation (heavy eyelids), dry mouth, and various other less common ones. If your BP spikes are very serious to the point of hypertensive urgency, then clonidine can be effective to bring down BP to prevent organ damage. Be aware also that you will become chemically dependent on this drug which means you will rebound (dangerous BP response) if you stop taking it suddenly.

You may want to talk to your doctor about longer acting alpha agents or other med choices. Also, an extended release oral clonidine should be receiving FDA approval soon(called Clonibid), and that may provide a smoother acting clonidine.